This invention relates to an ultrasonic atomizer for pumping up a liquid from a liquid vessel by an ultrasonic pump and atomizing the liquid by passing it through a mesh plate formed to have multiplicity of minute holes, an ultrasonic inhaler serving as one application of the ultrasonic atomizer, and a method of controlling the operation of the inhaler.
A known example of an ultrasonic atomizer of this type is described in the specification of Japanese Utility Model Application Laid-Open No. 3-15674. The atomizer described in this literature is characterized by use of a mesh plate having tapered minute holes which flare from one side of the plate toward the other. The mesh plate is arranged in such a manner that the side in which the minute holes have the openings of larger diameter opposes the upper end face of the pump shaft of an ultrasonic pump, and such that a minute gap is produced between the mesh plate and the upper end face of the pump shaft.
In an ultrasonic atomizer, it is important to achieve balance between the amount of liquid pumped by the ultrasonic pump and the amount of atomization produced by the mesh plate. When there is a minute gap between the upper end face of the pump shaft and the mesh plate, as in the document mentioned above, the amount of liquid pumped tends to be larger than the amount of liquid atomized. The liquid that is not atomized flows down from the gap to the upper portion (the horn) of the pump shaft and becomes a load on ultrasonic vibration at the horn. This causes an unstable spraying operation and can lead to cessation of operation in some cases.
Another problem is that the user""s fingers become soiled when liquid that has not been atomized flows out of the device. An important technical problem is assuring the liquid tightness of the device.
The number of minute holes formed in the mesh plate has a direct influence upon the amount of atomization. The greater the number of minute holes per unit surface area, the greater the amount of atomization. When the number of minute holes is increased, however, there is a decline in the strength of the mesh plate itself. There is a need for some expedient which can provide strength while allowing an increase in the number of minute holes.
Since the mesh plate described in the above-mentioned document is such that the minute holes have aperture diameters that differ on the two sides of the plate, care must be taken in terms of the orientation of these sides when the mesh plate is mounted in the atomizer.
An ultrasonic atomizer can be applied to an ultrasonic inhaler, as set forth above. Medicines of higher cost than inexpensive water and physiologic saline solutions are often used in inhalers. Accordingly, arranging it so that every drop of the medicine is used once the inhaler has been filled is important in terms of economy.
Another requirement of an inhaler is that the user repeat the operation for spraying the inhalant and halt this operation in conformity with breathing. Control of the spraying operation is achieved by having the user turn an operating switch on and off. However, turning the operating switch on and off often is troublesome or difficult particularly for the elderly or children. There is a need to arrange it so that the liquid is sprayed automatically and intermittently in conformity with the user""s breathing.
An object of the present invention is to provide a structure in an ultrasonic atomizer which makes it possible to achieve balance between amount of liquid pumped and amount of liquid atomized so that efficient and stable atomization can be obtained.
Another object of the present invention is to facilitate cleaning and replacement of the mesh plate.
A further object of the present invention is to provide a mesh plate having sufficient strength.
Yet another object of the present invention is to increase the amount of atomization by increasing the number of minute holes in the mesh plate.
Another object of the present invention is to improve liquid tightness of the device without limiting the vibration of a horn on the ultrasonic pump.
Another object of the present invention is to provide a structure which will not allow any excess liquid not atomized to flow out of the device.
A further object of the present invention is to enable effective utilization of liquid with which the device has been filled.
A further object of the present invention is to provide an inhaler, as well as a method of controlling the inhaler, in which it is possible to achieve automatic, intermittent spraying that conforms to the breathing of the user.
An ultrasonic atomizer according to the present invention comprises an ultrasonic pump comprising a pump shaft formed to have a pump bore passing through it axially and having open upper and lower ends, and an ultrasonic vibrator mounted on the pump shaft in the vicinity of the midpoint with respect to the axial direction, a liquid vessel provided at a position at which it is penetrated by a lower end of the pump shaft, a mesh plate placed on an upper end face of the pump shaft and formed to have a multiplicity of minute holes, and a biasing resilient member for biasing the mesh plate toward the upper end face of the pump shaft.
The pump shaft also is vibrated in the axial direction by vibration of the ultrasonic vibrator, whereby the liquid inside the liquid vessel is pumped up through the pump bore of the pump shaft. Since the mesh plate is urged against the upper end face of the pump by the resilient member, the mesh plate also vibrates by following up the motion of the pump shaft. Owing to the fact that the mesh plate is vibrated, and by virtue of the fact that the mesh plate is biased by the resilient member, the mesh plate acts as a type of valve which opens and closes the opening at the upper end of the pump bore in the pump shaft. The liquid pumped when the valve is opened is supplied to the mesh plate. When the valve is closed, the liquid is passed through the mesh plate so as to be atomized and sprayed. Since liquid in the amount pumped is atomized, good balance is achieved between the amount of liquid pumped and the amount of liquid atomized, and the spraying operation carried out is efficient and stable.
Since the mesh plate should be brought into pressured contact with the upper end face of the pump shaft at least in the vicinity of the opening at the upper end thereof, it is preferred that the following structure be adopted:
In a preferred embodiment, the upper end face of the pump shaft is formed to have a shape in which the upper end face is slightly and smoothly curved so as to attain maximum height at the position of the opening in the upper end of the pump bore and diminish in height as the periphery is approached.
In case of an arrangement in which the mesh plate is biased by the resilient member at a peripheral edge extending outwardly from the upper end face of the pump shaft, the mesh plate curves slightly. The curvature of the upper end face of the pump shaft, the elastic force of the resilient member and the strength of the mesh plate are decided in such a manner that the degree to which the mesh plate curves is less than the degree of curvature of the upper end face of the pump shaft.
In another embodiment, the upper end face of the pump shaft is formed to have a protuberance which projects in an area that includes the opening in the upper end of the pump bore.
In another embodiment, the mesh plate is formed to have a shape in which the central portion thereof is bent or curved slightly so as to point downward.
In a further embodiment, the biasing resilient member is a compression coil spring having a coil diameter which becomes progressively smaller as the mesh plate is approached, in such a manner that the mesh plate is biased at a position thereof situated on the upper end face of the pump shaft.
As set forth in the above-mentioned document, it is preferred that the mesh plate used be formed in such a manner that the minute holes flare outwardly in the direction extending from the top side to the bottom side of the mesh plate.
An arrangement recommended to heighten the density of the minute holes in the mesh plate is one in which the minute holes are formed at equal intervals long the sides of a multiplicity of regular hexagons whose diagonals vary at fixed distances.
The present invention also provides other improvements relating to the mesh plate. One is a mesh plate in which small areas devoid of the formation of minute holes are present in areas surrounded by minute holes. Since the mesh plate has a multiplicity of minute holes, it is nearly impossible to inspect all of the them. Accordingly, if minute holes to be inspected are specified using the small areas devoid of minute holes as a reference, it becomes possible to inspect minute holes at the same positions at all times.
In another mesh plate, an area devoid of the formation of minute holes is present over a region broader than the opening in the upper end of the pump bore of the pump shaft at a location opposing the opening in the upper end. By virtue of this arrangement, the above-described valve action is attained more effectively.
In yet another mesh plate, cut-outs of different size are formed in the periphery of the mesh plate at least at two locations other than locations having point symmetry about the center of the mesh plate.
The mesh plate is placed upon or attached to the step portion or some other location on a cap, described below. If a mesh-plate supporting member provided on such as a cap is provided with projections that mate with the two cut-outs mentioned above, it will be possible to attach and detach the mesh plate without mistaking the surface orientation of the mesh plate. This is convenient for mesh plates having minute holes whose openings differ in size depending upon the particular side.
In another preferred embodiment of an ultrasonic atomizer according to the present invention, there are further provided a housing, to which the liquid vessel is attached in a freely detachable manner, for supporting the ultrasonic pump, and a cap attached to a portion of the housing in a freely detachable manner so as to cover the upper end of the pump shaft. The top side of the cap is provided with a spray port and a step portion is formed for supporting the mesh plate at the perimeter thereof at a position beneath the spray port. The biasing resilient member is provided between a portion of the top side of the cap and the mesh plate.
When the cap is attached to the housing, the mesh plate is biased by the resilient member and brought into contact with the upper end face of the pump shaft. Thus, positioning of the mesh plate can be achieved with ease. Since the mesh plate is provided on the cap, cleaning or replacement (inclusive of replacement of the cap) is facilitated.
In yet another embodiment, the peripheral portion of the mesh plate is provided with an annular plate, or a spacer is provided between the mesh plate and the upper end face of the pump shaft, in order that the biasing force produced by the biasing member may be applied to the mesh plate uniformly.
The present invention provides a mesh plate having high strength. The mesh plate has two sides overall and is formed to have a multiplicity of minute holes passing through it from one side to the other side. Each minute hole flares outwardly from the one side to the other side, and a single plate-shaped body is deformed continuously at the location of each minute hole in such a manner that a groove or recess is formed between mutually adjacent minute holes on the one side.
The present invention further provides an effective seal structure in an ultrasonic atomizer. Specifically, in an ultrasonic atomizer comprising an ultrasonic pump having a pump shaft formed to have a pump bore passing through it axially and having open upper and lower ends, and an ultrasonic vibrator mounted on the pump shaft in the vicinity of the midpoint with respect to the axial direction, wherein a liquid inside a liquid vessel is pumped up from the lower end of the pump bore and the liquid is supplied to a mesh plate from the upper end of the pump bore so as to be sprayed, the present invention is characterized in that there is provided a bush for encircling and supporting liquid tightly a portion of the pump shaft of the ultrasonic pump excluding upper and lower end portions of the pump shaft, an annular seal lip, in intimate liquid-tight contact with a portion of the pump shaft situated higher than the ultrasonic vibrator, formed integrally at least at two locations, one above the other, on an upper portion of the bush, and a gap provided between the portion of the pump shaft and the bush between the annular seal lips at the at least two locations.
The liquid tightness of the ultrasonic pump within the bush is assured by the annular seal lips. Further, the bush is not made to contact, over its entire surface, the upper portion (horn) of the pump shaft, which undergoes large vibration; only the seal ribs are in partial intimate contact with the upper portion of the pump shaft. As a result, vibration of the horn is not attenuated.
The present invention further provides an ultrasonic atomizer having a reservoir for collecting overflowing liquid not atomized. Specifically, the ultrasonic atomizer according to this aspect of the present invention comprises an ultrasonic pump having a pump shaft formed to have a pump bore passing through it axially and having open upper and lower ends, and an ultrasonic vibrator mounted on the pump shaft in the vicinity of the midpoint with respect to the axial direction, a liquid vessel provided at a position at which it is penetrated by a lower end of the pump shaft, a mesh plate placed on an upper end face of the pump shaft and formed to have a multiplicity of minute holes, a biasing resilient member for biasing the mesh plate toward the upper end face of the pump shaft, a bush for encircling and supporting liquid tightly a portion of the pump shaft of the ultrasonic pump excluding upper and lower end portions of the pump shaft, a housing in which the bush is fitted liquid tightly, and a cap attached in a freely detachable manner to an annular projecting wall, which is formed on the housing about the upper end portion of the pump shaft, so as to cover the upper end portion of the pump shaft, a reservoir being formed with the top side of the bush serving as its bottom surface and at least one of the cap and annular projecting wall serving as its peripheral wall.
Liquid which has flowed into the reservoir is pumped along the pump shaft by the vibration thereof and is eventually atomized. Accordingly, the liquid does not overflow to the exterior of the device and does soil the fingers of the user. In addition, the liquid is used in an effective manner.
The present invention further provides an ultrasonic atomizer in which liquid inside the liquid vessel can be utilized without any being left unused.
The present invention is characterized in that, in an ultrasonic atomizer comprising a liquid vessel accommodating a liquid to be atomized, and an ultrasonic pump having a pump shaft formed to have a pump bore passing through it axially and having open upper and lower ends, and an ultrasonic vibrator mounted on the pump shaft, a lower end of the pump shaft is disposed in close proximity to a bottom surface or side surface of the liquid vessel in such a manner that residual liquid remaining inside the liquid vessel is pumped upon attaching itself to the lower end of the pump shaft by surface tension.
In a preferred embodiment, the liquid vessel is formed to have a recess for collecting the residual liquid remaining inside the liquid vessel, and the lower end of the pump shaft is disposed so as to face the recess.
Even if the amount of liquid remaining in the liquid vessel is small, the liquid attaches itself to the lower end of the pump shaft and is pumped by virtue of surface tension and ultrasonic vibration so that almost all of the liquid is used for spraying purposes. This is particularly effective when a costly medicine is used as the liquid.
Finally, the present invention provides an ultrasonic inhaler, and a method of controlling the same, in which the inhaler has a learning function and spraying is rendered intermittent automatically at a period that substantially coincides with the period at which an operating switch is operated by the user.
Specifically, the present invention provides an ultrasonic inhaler having an ultrasonic pump comprising a pump shaft formed to have a pump bore passing through it axially, and an ultrasonic vibrator mounted on the pump shaft, wherein liquid is pumped through the pump shaft and sprayed by ultrasonic vibration, characterized by comprising a drive circuit for driving the ultrasonic vibrator of the ultrasonic pump, an operating switch, first control means responsive to on/off operation of the operating switch for controlling drive of the ultrasonic vibrator by the drive circuit, and second control means which, in response to the operating switch being turned on and off one time or a plurality of times, is for deciding ON time and OFF time (as by calculating average value) in automatic intermittent operation on the basis of ON time and OFF time of the operating switch, and controlling the drive circuit in such a manner that the ultrasonic vibrator is driven at a period of the ON time and OFF time decided.
In an ultrasonic inhaler having an ultrasonic pump comprising a pump shaft formed to have a pump bore passing through it axially, and an ultrasonic vibrator mounted on the pump shaft, wherein liquid is pumped through the pump shaft and sprayed by the ultrasonic vibrator, a method of controlling the inhaler according to the present invention comprises driving the ultrasonic vibrator during time which an operating switch is ON when the operating switch has been turned on, measuring the on time, halting drive of the ultrasonic vibrator during time which the operating switch is OFF when the operating switch has been turned off, measuring the OFF time, deciding ON time and OFF time in automatic intermittent operation on the basis of the measured ON time and OFF time of the operating switch after the operating switch has been turned on and off a prescribed number of times, and driving the ultrasonic vibrator at a period of the on time and off time decided.
When the user turns the operating switch on and off a number of times in conformity with his or her own respiration, each of the on and off times is measured to decide on and off times suited to the user. The device thereafter enters an automatic intermittent-operation mode in which the spraying operation is performed intermittently at the period of the on and off times decided. This means that the user can breath without operating the operating switch any further.
In an embodiment, the second control means is started so as to perform the automatic intermittent operation in response to on/off operation of the operating switch repeated a requisite plurality of times. Alternatively, the second control means makes a transition to the automatic intermittent operation upon verifying that ON time of the operating switch the last time in the requisite plurality of times is greater than a first prescribed time.
In another embodiment, an automatic intermittent-operation mode switch is provided, the second control means is started so as perform the automatic intermittent operation in response to an input from the automatic intermittent-operation mode switch.
Preferably, third control means is provided for controlling the drive circuit so as to drive the ultrasonic vibrator continuously in response to ON time of the operating switch that is greater than a second predetermined time. As a result, spraying is performed continuously even if the user no longer presses the operating switch.
It is further preferred that a manual mode in which the user operates the operating switch at all times be provided.